Halak, 27, has appeared in five games this season posting a 3-0-0 record including a 2.10 goals-against average and an .889 save percentage, and is tied for the NHL lead with two shutouts. He had been out with a groin injury.
The Blues are 0-3-1 since starting the season with six wins in their first seven games.
The team also assigned goaltender Jake Allen to their American Hockey League (AHL) affiliate, Peoria Rivermen.
I've got a lot of experience and there's a lot of young guys. It's even making me excited a little more. It's kind of a new life. At my age, I feel like I know a lot of things what to do, but I just cannot do it anymore. It's a lot easier to tell them what to do because they've still got the legs and hands to do it. I just know things, but I cannot do them anymore.
— Jaromir Jagr after making his Panthers debut in a win against the Sabres on Saturday